Without limiting the scope of the present invention, its background will be described with reference to retrieving a well tool that was previously installed within a well, as an example.
After drilling a well that intersects a subterranean hydrocarbon bearing reservoir, a variety of well tools are often positioned in the wellbore during completion, production or remedial activities. For example, temporary packers are often set in the wellbore during the completion and production operating phases of the well. In addition, various operating tools including flow controllers such as plugs, chokes, valves and the like and safety devices such as safety valves are often retrievably positioned in the wellbore.
In the event that one of these well tools that has been previously installed within the wellbore requires removal, a pulling tool attached to a conveyance such as a wireline, a slickline or the like is typically run downhole to the location of the well tool to be removed. The pulling tool, which may include a fishing nose and latching assembly, is coupled to a fishing neck on the installed well tool. Thereafter, the well tool can be released from the wellbore and retrieved to the surface.
It has been found, however, that over time a well tool installed within the wellbore may become stuck in the wellbore and may require an impact or jarring force to be applied thereto in order to dislodge the well tool from its stuck position. In addition, it has been found that certain retrieval operations place significant demands on the integrity and strength of the conveyance, particularly in wells that are deep, deviated, inclined or horizontal due to the cumulative weight of the conveyance and frictional effects.
Accordingly, prior art retrieval tools can only apply a limited amount of force to directly dislodge a stuck well tool or to actuate a jarring tool such that an impact can be delivered to dislodge the stuck well tool. Therefore, a need has arisen for a downhole impact generator that can generate an impact to exert a jarring force on a stuck well tool such that the stuck well tools can be dislodged. A need has also arisen for such a downhole impact generator that will produce the necessary jarring force to dislodge well tools that have been installed and become stuck within deep, deviated, inclined or horizontal wellbores. Additionally, a need has also arisen for such a downhole impact generator that can be used to provide multiple impacts to dislodge stuck well tools. Further, a need has also arisen for such a downhole impact generator that will produce the necessary jarring force to dislodge well tools without requiring force to be generated via the conveyance.